sound/drivers/aloop.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Loopback soundcard
   4  *
   5  *  Original code:
   6  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   7  *
   8  *  More accurate positioning and full-duplex support:
   9  *  Copyright (c) Ahmet İnan <ainan at mathematik.uni-freiburg.de>
  10  *
  11  *  Major (almost complete) rewrite:
  12  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
  13  *
  14  *  A next major update in 2010 (separate timers for playback and capture):
  15  *  Copyright (c) Jaroslav Kysela <perex@perex.cz>
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/slab.h>
  21 #include <linux/time.h>
  22 #include <linux/wait.h>
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <sound/core.h>
  26 #include <sound/control.h>
  27 #include <sound/pcm.h>
  28 #include <sound/pcm_params.h>
  29 #include <sound/info.h>
  30 #include <sound/initval.h>
  31 #include <sound/timer.h>
  32
  33 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
  34 MODULE_DESCRIPTION("A loopback soundcard");
  35 MODULE_LICENSE("GPL");
  36
  37 #define MAX_PCM_SUBSTREAMS      8
  38
  39 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;      /* Index 0-MAX */
  40 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;       /* ID for this card */
  41 static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
  42 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
  43 static int pcm_notify[SNDRV_CARDS];
  44 static char *timer_source[SNDRV_CARDS];
  45
  46 module_param_array(index, int, NULL, 0444);
  47 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
  48 module_param_array(id, charp, NULL, 0444);
  49 MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
  50 module_param_array(enable, bool, NULL, 0444);
  51 MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
  52 module_param_array(pcm_substreams, int, NULL, 0444);
  53 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
  54 module_param_array(pcm_notify, int, NULL, 0444);
  55 MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
  56 module_param_array(timer_source, charp, NULL, 0444);
  57 MODULE_PARM_DESC(timer_source, "Sound card name or number and device/subdevice number of timer to be used. Empty string for jiffies timer [default].");
  58
  59 #define NO_PITCH 100000
  60
  61 #define CABLE_VALID_PLAYBACK    BIT(SNDRV_PCM_STREAM_PLAYBACK)
  62 #define CABLE_VALID_CAPTURE     BIT(SNDRV_PCM_STREAM_CAPTURE)
  63 #define CABLE_VALID_BOTH        (CABLE_VALID_PLAYBACK | CABLE_VALID_CAPTURE)
  64
  65 struct loopback_cable;
  66 struct loopback_pcm;
  67
  68 struct loopback_ops {
  69         /* optional
  70          * call in loopback->cable_lock
  71          */
  72         int (*open)(struct loopback_pcm *dpcm);
  73         /* required
  74          * call in cable->lock
  75          */
  76         int (*start)(struct loopback_pcm *dpcm);
  77         /* required
  78          * call in cable->lock
  79          */
  80         int (*stop)(struct loopback_pcm *dpcm);
  81         /* optional */
  82         int (*stop_sync)(struct loopback_pcm *dpcm);
  83         /* optional */
  84         int (*close_substream)(struct loopback_pcm *dpcm);
  85         /* optional
  86          * call in loopback->cable_lock
  87          */
  88         int (*close_cable)(struct loopback_pcm *dpcm);
  89         /* optional
  90          * call in cable->lock
  91          */
  92         unsigned int (*pos_update)(struct loopback_cable *cable);
  93         /* optional */
  94         void (*dpcm_info)(struct loopback_pcm *dpcm,
  95                           struct snd_info_buffer *buffer);
  96 };
  97
  98 struct loopback_cable {
  99         spinlock_t lock;
 100         struct loopback_pcm *streams[2];
 101         struct snd_pcm_hardware hw;
 102         /* flags */
 103         unsigned int valid;
 104         unsigned int running;
 105         unsigned int pause;
 106         /* timer specific */
 107         const struct loopback_ops *ops;
 108         /* If sound timer is used */
 109         struct {
 110                 int stream;
 111                 struct snd_timer_id id;
 112                 struct work_struct event_work;
 113                 struct snd_timer_instance *instance;
 114         } snd_timer;
 115 };
 116
 117 struct loopback_setup {
 118         unsigned int notify: 1;
 119         unsigned int rate_shift;
 120         snd_pcm_format_t format;
 121         unsigned int rate;
 122         unsigned int channels;
 123         struct snd_ctl_elem_id active_id;
 124         struct snd_ctl_elem_id format_id;
 125         struct snd_ctl_elem_id rate_id;
 126         struct snd_ctl_elem_id channels_id;
 127 };
 128
 129 struct loopback {
 130         struct snd_card *card;
 131         struct mutex cable_lock;
 132         struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];
 133         struct snd_pcm *pcm[2];
 134         struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
 135         const char *timer_source;
 136 };
 137
 138 struct loopback_pcm {
 139         struct loopback *loopback;
 140         struct snd_pcm_substream *substream;
 141         struct loopback_cable *cable;
 142         unsigned int pcm_buffer_size;
 143         unsigned int buf_pos;   /* position in buffer */
 144         unsigned int silent_size;
 145         /* PCM parameters */
 146         unsigned int pcm_period_size;
 147         unsigned int pcm_bps;           /* bytes per second */
 148         unsigned int pcm_salign;        /* bytes per sample * channels */
 149         unsigned int pcm_rate_shift;    /* rate shift value */
 150         /* flags */
 151         unsigned int period_update_pending :1;
 152         /* timer stuff */
 153         unsigned int irq_pos;           /* fractional IRQ position in jiffies
 154                                          * ticks
 155                                          */
 156         unsigned int period_size_frac;  /* period size in jiffies ticks */
 157         unsigned int last_drift;
 158         unsigned long last_jiffies;
 159         /* If jiffies timer is used */
 160         struct timer_list timer;
 161 };
 162
 163 static struct platform_device *devices[SNDRV_CARDS];
 164
 165 static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
 166 {
 167         if (dpcm->pcm_rate_shift == NO_PITCH) {
 168                 x /= HZ;
 169         } else {
 170                 x = div_u64(NO_PITCH * (unsigned long long)x,
 171                             HZ * (unsigned long long)dpcm->pcm_rate_shift);
 172         }
 173         return x - (x % dpcm->pcm_salign);
 174 }
 175
 176 static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)
 177 {
 178         if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */
 179                 return x * HZ;
 180         } else {
 181                 x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ,
 182                             NO_PITCH);
 183         }
 184         return x;
 185 }
 186
 187 static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
 188 {
 189         int device = dpcm->substream->pstr->pcm->device;
 190
 191         if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 192                 device ^= 1;
 193         return &dpcm->loopback->setup[dpcm->substream->number][device];
 194 }
 195
 196 static inline unsigned int get_notify(struct loopback_pcm *dpcm)
 197 {
 198         return get_setup(dpcm)->notify;
 199 }
 200
 201 static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)
 202 {
 203         return get_setup(dpcm)->rate_shift;
 204 }
 205
 206 /* call in cable->lock */
 207 static int loopback_jiffies_timer_start(struct loopback_pcm *dpcm)
 208 {
 209         unsigned long tick;
 210         unsigned int rate_shift = get_rate_shift(dpcm);
 211
 212         if (rate_shift != dpcm->pcm_rate_shift) {
 213                 dpcm->pcm_rate_shift = rate_shift;
 214                 dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);
 215         }
 216         if (dpcm->period_size_frac <= dpcm->irq_pos) {
 217                 dpcm->irq_pos %= dpcm->period_size_frac;
 218                 dpcm->period_update_pending = 1;
 219         }
 220         tick = dpcm->period_size_frac - dpcm->irq_pos;
 221         tick = DIV_ROUND_UP(tick, dpcm->pcm_bps);
 222         mod_timer(&dpcm->timer, jiffies + tick);
 223
 224         return 0;
 225 }
 226
 227 /* call in cable->lock */
 228 static int loopback_snd_timer_start(struct loopback_pcm *dpcm)
 229 {
 230         struct loopback_cable *cable = dpcm->cable;
 231         int err;
 232
 233         /* Loopback device has to use same period as timer card. Therefore
 234          * wake up for each snd_pcm_period_elapsed() call of timer card.
 235          */
 236         err = snd_timer_start(cable->snd_timer.instance, 1);
 237         if (err < 0) {
 238                 /* do not report error if trying to start but already
 239                  * running. For example called by opposite substream
 240                  * of the same cable
 241                  */
 242                 if (err == -EBUSY)
 243                         return 0;
 244
 245                 pcm_err(dpcm->substream->pcm,
 246                         "snd_timer_start(%d,%d,%d) failed with %d",
 247                         cable->snd_timer.id.card,
 248                         cable->snd_timer.id.device,
 249                         cable->snd_timer.id.subdevice,
 250                         err);
 251         }
 252
 253         return err;
 254 }
 255
 256 /* call in cable->lock */
 257 static inline int loopback_jiffies_timer_stop(struct loopback_pcm *dpcm)
 258 {
 259         del_timer(&dpcm->timer);
 260         dpcm->timer.expires = 0;
 261
 262         return 0;
 263 }
 264
 265 /* call in cable->lock */
 266 static int loopback_snd_timer_stop(struct loopback_pcm *dpcm)
 267 {
 268         struct loopback_cable *cable = dpcm->cable;
 269         int err;
 270
 271         /* only stop if both devices (playback and capture) are not running */
 272         if (cable->running ^ cable->pause)
 273                 return 0;
 274
 275         err = snd_timer_stop(cable->snd_timer.instance);
 276         if (err < 0) {
 277                 pcm_err(dpcm->substream->pcm,
 278                         "snd_timer_stop(%d,%d,%d) failed with %d",
 279                         cable->snd_timer.id.card,
 280                         cable->snd_timer.id.device,
 281                         cable->snd_timer.id.subdevice,
 282                         err);
 283         }
 284
 285         return err;
 286 }
 287
 288 static inline int loopback_jiffies_timer_stop_sync(struct loopback_pcm *dpcm)
 289 {
 290         del_timer_sync(&dpcm->timer);
 291
 292         return 0;
 293 }
 294
 295 /* call in loopback->cable_lock */
 296 static int loopback_snd_timer_close_cable(struct loopback_pcm *dpcm)
 297 {
 298         struct loopback_cable *cable = dpcm->cable;
 299
 300         /* snd_timer was not opened */
 301         if (!cable->snd_timer.instance)
 302                 return 0;
 303
 304         /* will only be called from free_cable() when other stream was
 305          * already closed. Other stream cannot be reopened as long as
 306          * loopback->cable_lock is locked. Therefore no need to lock
 307          * cable->lock;
 308          */
 309         snd_timer_close(cable->snd_timer.instance);
 310
 311         /* wait till drain work has finished if requested */
 312         cancel_work_sync(&cable->snd_timer.event_work);
 313
 314         snd_timer_instance_free(cable->snd_timer.instance);
 315         memset(&cable->snd_timer, 0, sizeof(cable->snd_timer));
 316
 317         return 0;
 318 }
 319
 320 static int loopback_check_format(struct loopback_cable *cable, int stream)
 321 {
 322         struct snd_pcm_runtime *runtime, *cruntime;
 323         struct loopback_setup *setup;
 324         struct snd_card *card;
 325         int check;
 326
 327         if (cable->valid != CABLE_VALID_BOTH) {
 328                 if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 329                         goto __notify;
 330                 return 0;
 331         }
 332         runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
 333                                                         substream->runtime;
 334         cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
 335                                                         substream->runtime;
 336         check = runtime->format != cruntime->format ||
 337                 runtime->rate != cruntime->rate ||
 338                 runtime->channels != cruntime->channels;
 339         if (!check)
 340                 return 0;
 341         if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 342                 return -EIO;
 343         } else {
 344                 snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
 345                                         substream, SNDRV_PCM_STATE_DRAINING);
 346               __notify:
 347                 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
 348                                                         substream->runtime;
 349                 setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);
 350                 card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;
 351                 if (setup->format != runtime->format) {
 352                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 353                                                         &setup->format_id);
 354                         setup->format = runtime->format;
 355                 }
 356                 if (setup->rate != runtime->rate) {
 357                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 358                                                         &setup->rate_id);
 359                         setup->rate = runtime->rate;
 360                 }
 361                 if (setup->channels != runtime->channels) {
 362                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 363                                                         &setup->channels_id);
 364                         setup->channels = runtime->channels;
 365                 }
 366         }
 367         return 0;
 368 }
 369
 370 static void loopback_active_notify(struct loopback_pcm *dpcm)
 371 {
 372         snd_ctl_notify(dpcm->loopback->card,
 373                        SNDRV_CTL_EVENT_MASK_VALUE,
 374                        &get_setup(dpcm)->active_id);
 375 }
 376
 377 static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
 378 {
 379         struct snd_pcm_runtime *runtime = substream->runtime;
 380         struct loopback_pcm *dpcm = runtime->private_data;
 381         struct loopback_cable *cable = dpcm->cable;
 382         int err = 0, stream = 1 << substream->stream;
 383
 384         switch (cmd) {
 385         case SNDRV_PCM_TRIGGER_START:
 386                 err = loopback_check_format(cable, substream->stream);
 387                 if (err < 0)
 388                         return err;
 389                 dpcm->last_jiffies = jiffies;
 390                 dpcm->pcm_rate_shift = 0;
 391                 dpcm->last_drift = 0;
 392                 spin_lock(&cable->lock);
 393                 cable->running |= stream;
 394                 cable->pause &= ~stream;
 395                 err = cable->ops->start(dpcm);
 396                 spin_unlock(&cable->lock);
 397                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 398                         loopback_active_notify(dpcm);
 399                 break;
 400         case SNDRV_PCM_TRIGGER_STOP:
 401                 spin_lock(&cable->lock);
 402                 cable->running &= ~stream;
 403                 cable->pause &= ~stream;
 404                 err = cable->ops->stop(dpcm);
 405                 spin_unlock(&cable->lock);
 406                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 407                         loopback_active_notify(dpcm);
 408                 break;
 409         case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 410         case SNDRV_PCM_TRIGGER_SUSPEND:
 411                 spin_lock(&cable->lock);
 412                 cable->pause |= stream;
 413                 err = cable->ops->stop(dpcm);
 414                 spin_unlock(&cable->lock);
 415                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 416                         loopback_active_notify(dpcm);
 417                 break;
 418         case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 419         case SNDRV_PCM_TRIGGER_RESUME:
 420                 spin_lock(&cable->lock);
 421                 dpcm->last_jiffies = jiffies;
 422                 cable->pause &= ~stream;
 423                 err = cable->ops->start(dpcm);
 424                 spin_unlock(&cable->lock);
 425                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 426                         loopback_active_notify(dpcm);
 427                 break;
 428         default:
 429                 return -EINVAL;
 430         }
 431         return err;
 432 }
 433
 434 static void params_change(struct snd_pcm_substream *substream)
 435 {
 436         struct snd_pcm_runtime *runtime = substream->runtime;
 437         struct loopback_pcm *dpcm = runtime->private_data;
 438         struct loopback_cable *cable = dpcm->cable;
 439
 440         cable->hw.formats = pcm_format_to_bits(runtime->format);
 441         cable->hw.rate_min = runtime->rate;
 442         cable->hw.rate_max = runtime->rate;
 443         cable->hw.channels_min = runtime->channels;
 444         cable->hw.channels_max = runtime->channels;
 445
 446         if (cable->snd_timer.instance) {
 447                 cable->hw.period_bytes_min =
 448                                 frames_to_bytes(runtime, runtime->period_size);
 449                 cable->hw.period_bytes_max = cable->hw.period_bytes_min;
 450         }
 451
 452 }
 453
 454 static int loopback_prepare(struct snd_pcm_substream *substream)
 455 {
 456         struct snd_pcm_runtime *runtime = substream->runtime;
 457         struct loopback_pcm *dpcm = runtime->private_data;
 458         struct loopback_cable *cable = dpcm->cable;
 459         int err, bps, salign;
 460
 461         if (cable->ops->stop_sync) {
 462                 err = cable->ops->stop_sync(dpcm);
 463                 if (err < 0)
 464                         return err;
 465         }
 466
 467         salign = (snd_pcm_format_physical_width(runtime->format) *
 468                                                 runtime->channels) / 8;
 469         bps = salign * runtime->rate;
 470         if (bps <= 0 || salign <= 0)
 471                 return -EINVAL;
 472
 473         dpcm->buf_pos = 0;
 474         dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
 475         if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
 476                 /* clear capture buffer */
 477                 dpcm->silent_size = dpcm->pcm_buffer_size;
 478                 snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
 479                                            runtime->buffer_size * runtime->channels);
 480         }
 481
 482         dpcm->irq_pos = 0;
 483         dpcm->period_update_pending = 0;
 484         dpcm->pcm_bps = bps;
 485         dpcm->pcm_salign = salign;
 486         dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);
 487
 488         mutex_lock(&dpcm->loopback->cable_lock);
 489         if (!(cable->valid & ~(1 << substream->stream)) ||
 490             (get_setup(dpcm)->notify &&
 491              substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
 492                 params_change(substream);
 493         cable->valid |= 1 << substream->stream;
 494         mutex_unlock(&dpcm->loopback->cable_lock);
 495
 496         return 0;
 497 }
 498
 499 static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
 500 {
 501         struct snd_pcm_runtime *runtime = dpcm->substream->runtime;
 502         char *dst = runtime->dma_area;
 503         unsigned int dst_off = dpcm->buf_pos;
 504
 505         if (dpcm->silent_size >= dpcm->pcm_buffer_size)
 506                 return;
 507         if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)
 508                 bytes = dpcm->pcm_buffer_size - dpcm->silent_size;
 509
 510         for (;;) {
 511                 unsigned int size = bytes;
 512                 if (dst_off + size > dpcm->pcm_buffer_size)
 513                         size = dpcm->pcm_buffer_size - dst_off;
 514                 snd_pcm_format_set_silence(runtime->format, dst + dst_off,
 515                                            bytes_to_frames(runtime, size) *
 516                                                 runtime->channels);
 517                 dpcm->silent_size += size;
 518                 bytes -= size;
 519                 if (!bytes)
 520                         break;
 521                 dst_off = 0;
 522         }
 523 }
 524
 525 static void copy_play_buf(struct loopback_pcm *play,
 526                           struct loopback_pcm *capt,
 527                           unsigned int bytes)
 528 {
 529         struct snd_pcm_runtime *runtime = play->substream->runtime;
 530         char *src = runtime->dma_area;
 531         char *dst = capt->substream->runtime->dma_area;
 532         unsigned int src_off = play->buf_pos;
 533         unsigned int dst_off = capt->buf_pos;
 534         unsigned int clear_bytes = 0;
 535
 536         /* check if playback is draining, trim the capture copy size
 537          * when our pointer is at the end of playback ring buffer */
 538         if (runtime->status->state == SNDRV_PCM_STATE_DRAINING &&
 539             snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) {
 540                 snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
 541                 appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
 542                 appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
 543                 appl_ptr1 += play->buf_pos / play->pcm_salign;
 544                 if (appl_ptr < appl_ptr1)
 545                         appl_ptr1 -= runtime->buffer_size;
 546                 diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
 547                 if (diff < bytes) {
 548                         clear_bytes = bytes - diff;
 549                         bytes = diff;
 550                 }
 551         }
 552
 553         for (;;) {
 554                 unsigned int size = bytes;
 555                 if (src_off + size > play->pcm_buffer_size)
 556                         size = play->pcm_buffer_size - src_off;
 557                 if (dst_off + size > capt->pcm_buffer_size)
 558                         size = capt->pcm_buffer_size - dst_off;
 559                 memcpy(dst + dst_off, src + src_off, size);
 560                 capt->silent_size = 0;
 561                 bytes -= size;
 562                 if (!bytes)
 563                         break;
 564                 src_off = (src_off + size) % play->pcm_buffer_size;
 565                 dst_off = (dst_off + size) % capt->pcm_buffer_size;
 566         }
 567
 568         if (clear_bytes > 0) {
 569                 clear_capture_buf(capt, clear_bytes);
 570                 capt->silent_size = 0;
 571         }
 572 }
 573
 574 static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,
 575                                          unsigned int jiffies_delta)
 576 {
 577         unsigned long last_pos;
 578         unsigned int delta;
 579
 580         last_pos = byte_pos(dpcm, dpcm->irq_pos);
 581         dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;
 582         delta = byte_pos(dpcm, dpcm->irq_pos) - last_pos;
 583         if (delta >= dpcm->last_drift)
 584                 delta -= dpcm->last_drift;
 585         dpcm->last_drift = 0;
 586         if (dpcm->irq_pos >= dpcm->period_size_frac) {
 587                 dpcm->irq_pos %= dpcm->period_size_frac;
 588                 dpcm->period_update_pending = 1;
 589         }
 590         return delta;
 591 }
 592
 593 static inline void bytepos_finish(struct loopback_pcm *dpcm,
 594                                   unsigned int delta)
 595 {
 596         dpcm->buf_pos += delta;
 597         dpcm->buf_pos %= dpcm->pcm_buffer_size;
 598 }
 599
 600 /* call in cable->lock */
 601 static unsigned int loopback_jiffies_timer_pos_update
 602                 (struct loopback_cable *cable)
 603 {
 604         struct loopback_pcm *dpcm_play =
 605                         cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
 606         struct loopback_pcm *dpcm_capt =
 607                         cable->streams[SNDRV_PCM_STREAM_CAPTURE];
 608         unsigned long delta_play = 0, delta_capt = 0;
 609         unsigned int running, count1, count2;
 610
 611         running = cable->running ^ cable->pause;
 612         if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
 613                 delta_play = jiffies - dpcm_play->last_jiffies;
 614                 dpcm_play->last_jiffies += delta_play;
 615         }
 616
 617         if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
 618                 delta_capt = jiffies - dpcm_capt->last_jiffies;
 619                 dpcm_capt->last_jiffies += delta_capt;
 620         }
 621
 622         if (delta_play == 0 && delta_capt == 0)
 623                 goto unlock;
 624
 625         if (delta_play > delta_capt) {
 626                 count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);
 627                 bytepos_finish(dpcm_play, count1);
 628                 delta_play = delta_capt;
 629         } else if (delta_play < delta_capt) {
 630                 count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);
 631                 clear_capture_buf(dpcm_capt, count1);
 632                 bytepos_finish(dpcm_capt, count1);
 633                 delta_capt = delta_play;
 634         }
 635
 636         if (delta_play == 0 && delta_capt == 0)
 637                 goto unlock;
 638
 639         /* note delta_capt == delta_play at this moment */
 640         count1 = bytepos_delta(dpcm_play, delta_play);
 641         count2 = bytepos_delta(dpcm_capt, delta_capt);
 642         if (count1 < count2) {
 643                 dpcm_capt->last_drift = count2 - count1;
 644                 count1 = count2;
 645         } else if (count1 > count2) {
 646                 dpcm_play->last_drift = count1 - count2;
 647         }
 648         copy_play_buf(dpcm_play, dpcm_capt, count1);
 649         bytepos_finish(dpcm_play, count1);
 650         bytepos_finish(dpcm_capt, count1);
 651  unlock:
 652         return running;
 653 }
 654
 655 static void loopback_jiffies_timer_function(struct timer_list *t)
 656 {
 657         struct loopback_pcm *dpcm = from_timer(dpcm, t, timer);
 658         unsigned long flags;
 659
 660         spin_lock_irqsave(&dpcm->cable->lock, flags);
 661         if (loopback_jiffies_timer_pos_update(dpcm->cable) &
 662                         (1 << dpcm->substream->stream)) {
 663                 loopback_jiffies_timer_start(dpcm);
 664                 if (dpcm->period_update_pending) {
 665                         dpcm->period_update_pending = 0;
 666                         spin_unlock_irqrestore(&dpcm->cable->lock, flags);
 667                         /* need to unlock before calling below */
 668                         snd_pcm_period_elapsed(dpcm->substream);
 669                         return;
 670                 }
 671         }
 672         spin_unlock_irqrestore(&dpcm->cable->lock, flags);
 673 }
 674
 675 /* call in cable->lock */
 676 static int loopback_snd_timer_check_resolution(struct snd_pcm_runtime *runtime,
 677                                                unsigned long resolution)
 678 {
 679         if (resolution != runtime->timer_resolution) {
 680                 struct loopback_pcm *dpcm = runtime->private_data;
 681                 struct loopback_cable *cable = dpcm->cable;
 682                 /* Worst case estimation of possible values for resolution
 683                  * resolution <= (512 * 1024) frames / 8kHz in nsec
 684                  * resolution <= 65.536.000.000 nsec
 685                  *
 686                  * period_size <= 65.536.000.000 nsec / 1000nsec/usec * 192kHz +
 687                  *  500.000
 688                  * period_size <= 12.582.912.000.000  <64bit
 689                  *  / 1.000.000 usec/sec
 690                  */
 691                 snd_pcm_uframes_t period_size_usec =
 692                                 resolution / 1000 * runtime->rate;
 693                 /* round to nearest sample rate */
 694                 snd_pcm_uframes_t period_size =
 695                                 (period_size_usec + 500 * 1000) / (1000 * 1000);
 696
 697                 pcm_err(dpcm->substream->pcm,
 698                         "Period size (%lu frames) of loopback device is not corresponding to timer resolution (%lu nsec = %lu frames) of card timer %d,%d,%d. Use period size of %lu frames for loopback device.",
 699                         runtime->period_size, resolution, period_size,
 700                         cable->snd_timer.id.card,
 701                         cable->snd_timer.id.device,
 702                         cable->snd_timer.id.subdevice,
 703                         period_size);
 704                 return -EINVAL;
 705         }
 706         return 0;
 707 }
 708
 709 static void loopback_snd_timer_period_elapsed(struct loopback_cable *cable,
 710                                               int event,
 711                                               unsigned long resolution)
 712 {
 713         struct loopback_pcm *dpcm_play, *dpcm_capt;
 714         struct snd_pcm_substream *substream_play, *substream_capt;
 715         struct snd_pcm_runtime *valid_runtime;
 716         unsigned int running, elapsed_bytes;
 717         unsigned long flags;
 718
 719         spin_lock_irqsave(&cable->lock, flags);
 720         running = cable->running ^ cable->pause;
 721         /* no need to do anything if no stream is running */
 722         if (!running) {
 723                 spin_unlock_irqrestore(&cable->lock, flags);
 724                 return;
 725         }
 726
 727         dpcm_play = cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
 728         dpcm_capt = cable->streams[SNDRV_PCM_STREAM_CAPTURE];
 729
 730         if (event == SNDRV_TIMER_EVENT_MSTOP) {
 731                 if (!dpcm_play ||
 732                     dpcm_play->substream->runtime->status->state !=
 733                                 SNDRV_PCM_STATE_DRAINING) {
 734                         spin_unlock_irqrestore(&cable->lock, flags);
 735                         return;
 736                 }
 737         }
 738
 739         substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
 740                         dpcm_play->substream : NULL;
 741         substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
 742                         dpcm_capt->substream : NULL;
 743         valid_runtime = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
 744                                 dpcm_play->substream->runtime :
 745                                 dpcm_capt->substream->runtime;
 746
 747         /* resolution is only valid for SNDRV_TIMER_EVENT_TICK events */
 748         if (event == SNDRV_TIMER_EVENT_TICK) {
 749                 /* The hardware rules guarantee that playback and capture period
 750                  * are the same. Therefore only one device has to be checked
 751                  * here.
 752                  */
 753                 if (loopback_snd_timer_check_resolution(valid_runtime,
 754                                                         resolution) < 0) {
 755                         spin_unlock_irqrestore(&cable->lock, flags);
 756                         if (substream_play)
 757                                 snd_pcm_stop_xrun(substream_play);
 758                         if (substream_capt)
 759                                 snd_pcm_stop_xrun(substream_capt);
 760                         return;
 761                 }
 762         }
 763
 764         elapsed_bytes = frames_to_bytes(valid_runtime,
 765                                         valid_runtime->period_size);
 766         /* The same timer interrupt is used for playback and capture device */
 767         if ((running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) &&
 768             (running & (1 << SNDRV_PCM_STREAM_CAPTURE))) {
 769                 copy_play_buf(dpcm_play, dpcm_capt, elapsed_bytes);
 770                 bytepos_finish(dpcm_play, elapsed_bytes);
 771                 bytepos_finish(dpcm_capt, elapsed_bytes);
 772         } else if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
 773                 bytepos_finish(dpcm_play, elapsed_bytes);
 774         } else if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
 775                 clear_capture_buf(dpcm_capt, elapsed_bytes);
 776                 bytepos_finish(dpcm_capt, elapsed_bytes);
 777         }
 778         spin_unlock_irqrestore(&cable->lock, flags);
 779
 780         if (substream_play)
 781                 snd_pcm_period_elapsed(substream_play);
 782         if (substream_capt)
 783                 snd_pcm_period_elapsed(substream_capt);
 784 }
 785
 786 static void loopback_snd_timer_function(struct snd_timer_instance *timeri,
 787                                         unsigned long resolution,
 788                                         unsigned long ticks)
 789 {
 790         struct loopback_cable *cable = timeri->callback_data;
 791
 792         loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_TICK,
 793                                           resolution);
 794 }
 795
 796 static void loopback_snd_timer_work(struct work_struct *work)
 797 {
 798         struct loopback_cable *cable;
 799
 800         cable = container_of(work, struct loopback_cable, snd_timer.event_work);
 801         loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_MSTOP, 0);
 802 }
 803
 804 static void loopback_snd_timer_event(struct snd_timer_instance *timeri,
 805                                      int event,
 806                                      struct timespec64 *tstamp,
 807                                      unsigned long resolution)
 808 {
 809         /* Do not lock cable->lock here because timer->lock is already hold.
 810          * There are other functions which first lock cable->lock and than
 811          * timer->lock e.g.
 812          * loopback_trigger()
 813          * spin_lock(&cable->lock)
 814          * loopback_snd_timer_start()
 815          * snd_timer_start()
 816          * spin_lock(&timer->lock)
 817          * Therefore when using the oposit order of locks here it could result
 818          * in a deadlock.
 819          */
 820
 821         if (event == SNDRV_TIMER_EVENT_MSTOP) {
 822                 struct loopback_cable *cable = timeri->callback_data;
 823
 824                 /* sound card of the timer was stopped. Therefore there will not
 825                  * be any further timer callbacks. Due to this forward audio
 826                  * data from here if in draining state. When still in running
 827                  * state the streaming will be aborted by the usual timeout. It
 828                  * should not be aborted here because may be the timer sound
 829                  * card does only a recovery and the timer is back soon.
 830                  * This work triggers loopback_snd_timer_work()
 831                  */
 832                 schedule_work(&cable->snd_timer.event_work);
 833         }
 834 }
 835
 836 static void loopback_jiffies_timer_dpcm_info(struct loopback_pcm *dpcm,
 837                                              struct snd_info_buffer *buffer)
 838 {
 839         snd_iprintf(buffer, "    update_pending:\t%u\n",
 840                     dpcm->period_update_pending);
 841         snd_iprintf(buffer, "    irq_pos:\t\t%u\n", dpcm->irq_pos);
 842         snd_iprintf(buffer, "    period_frac:\t%u\n", dpcm->period_size_frac);
 843         snd_iprintf(buffer, "    last_jiffies:\t%lu (%lu)\n",
 844                     dpcm->last_jiffies, jiffies);
 845         snd_iprintf(buffer, "    timer_expires:\t%lu\n", dpcm->timer.expires);
 846 }
 847
 848 static void loopback_snd_timer_dpcm_info(struct loopback_pcm *dpcm,
 849                                          struct snd_info_buffer *buffer)
 850 {
 851         struct loopback_cable *cable = dpcm->cable;
 852
 853         snd_iprintf(buffer, "    sound timer:\thw:%d,%d,%d\n",
 854                     cable->snd_timer.id.card,
 855                     cable->snd_timer.id.device,
 856                     cable->snd_timer.id.subdevice);
 857         snd_iprintf(buffer, "    timer open:\t\t%s\n",
 858                     (cable->snd_timer.stream == SNDRV_PCM_STREAM_CAPTURE) ?
 859                             "capture" : "playback");
 860 }
 861
 862 static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)
 863 {
 864         struct snd_pcm_runtime *runtime = substream->runtime;
 865         struct loopback_pcm *dpcm = runtime->private_data;
 866         snd_pcm_uframes_t pos;
 867
 868         spin_lock(&dpcm->cable->lock);
 869         if (dpcm->cable->ops->pos_update)
 870                 dpcm->cable->ops->pos_update(dpcm->cable);
 871         pos = dpcm->buf_pos;
 872         spin_unlock(&dpcm->cable->lock);
 873         return bytes_to_frames(runtime, pos);
 874 }
 875
 876 static const struct snd_pcm_hardware loopback_pcm_hardware =
 877 {
 878         .info =         (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
 879                          SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE |
 880                          SNDRV_PCM_INFO_RESUME),
 881         .formats =      (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
 882                          SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
 883                          SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |
 884                          SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |
 885                          SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),
 886         .rates =        SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
 887         .rate_min =             8000,
 888         .rate_max =             192000,
 889         .channels_min =         1,
 890         .channels_max =         32,
 891         .buffer_bytes_max =     2 * 1024 * 1024,
 892         .period_bytes_min =     64,
 893         /* note check overflow in frac_pos() using pcm_rate_shift before
 894            changing period_bytes_max value */
 895         .period_bytes_max =     1024 * 1024,
 896         .periods_min =          1,
 897         .periods_max =          1024,
 898         .fifo_size =            0,
 899 };
 900
 901 static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
 902 {
 903         struct loopback_pcm *dpcm = runtime->private_data;
 904         kfree(dpcm);
 905 }
 906
 907 static int loopback_hw_free(struct snd_pcm_substream *substream)
 908 {
 909         struct snd_pcm_runtime *runtime = substream->runtime;
 910         struct loopback_pcm *dpcm = runtime->private_data;
 911         struct loopback_cable *cable = dpcm->cable;
 912
 913         mutex_lock(&dpcm->loopback->cable_lock);
 914         cable->valid &= ~(1 << substream->stream);
 915         mutex_unlock(&dpcm->loopback->cable_lock);
 916         return 0;
 917 }
 918
 919 static unsigned int get_cable_index(struct snd_pcm_substream *substream)
 920 {
 921         if (!substream->pcm->device)
 922                 return substream->stream;
 923         else
 924                 return !substream->stream;
 925 }
 926
 927 static int rule_format(struct snd_pcm_hw_params *params,
 928                        struct snd_pcm_hw_rule *rule)
 929 {
 930         struct loopback_pcm *dpcm = rule->private;
 931         struct loopback_cable *cable = dpcm->cable;
 932         struct snd_mask m;
 933
 934         snd_mask_none(&m);
 935         mutex_lock(&dpcm->loopback->cable_lock);
 936         m.bits[0] = (u_int32_t)cable->hw.formats;
 937         m.bits[1] = (u_int32_t)(cable->hw.formats >> 32);
 938         mutex_unlock(&dpcm->loopback->cable_lock);
 939         return snd_mask_refine(hw_param_mask(params, rule->var), &m);
 940 }
 941
 942 static int rule_rate(struct snd_pcm_hw_params *params,
 943                      struct snd_pcm_hw_rule *rule)
 944 {
 945         struct loopback_pcm *dpcm = rule->private;
 946         struct loopback_cable *cable = dpcm->cable;
 947         struct snd_interval t;
 948
 949         mutex_lock(&dpcm->loopback->cable_lock);
 950         t.min = cable->hw.rate_min;
 951         t.max = cable->hw.rate_max;
 952         mutex_unlock(&dpcm->loopback->cable_lock);
 953         t.openmin = t.openmax = 0;
 954         t.integer = 0;
 955         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 956 }
 957
 958 static int rule_channels(struct snd_pcm_hw_params *params,
 959                          struct snd_pcm_hw_rule *rule)
 960 {
 961         struct loopback_pcm *dpcm = rule->private;
 962         struct loopback_cable *cable = dpcm->cable;
 963         struct snd_interval t;
 964
 965         mutex_lock(&dpcm->loopback->cable_lock);
 966         t.min = cable->hw.channels_min;
 967         t.max = cable->hw.channels_max;
 968         mutex_unlock(&dpcm->loopback->cable_lock);
 969         t.openmin = t.openmax = 0;
 970         t.integer = 0;
 971         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 972 }
 973
 974 static int rule_period_bytes(struct snd_pcm_hw_params *params,
 975                              struct snd_pcm_hw_rule *rule)
 976 {
 977         struct loopback_pcm *dpcm = rule->private;
 978         struct loopback_cable *cable = dpcm->cable;
 979         struct snd_interval t;
 980
 981         mutex_lock(&dpcm->loopback->cable_lock);
 982         t.min = cable->hw.period_bytes_min;
 983         t.max = cable->hw.period_bytes_max;
 984         mutex_unlock(&dpcm->loopback->cable_lock);
 985         t.openmin = 0;
 986         t.openmax = 0;
 987         t.integer = 0;
 988         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 989 }
 990
 991 static void free_cable(struct snd_pcm_substream *substream)
 992 {
 993         struct loopback *loopback = substream->private_data;
 994         int dev = get_cable_index(substream);
 995         struct loopback_cable *cable;
 996
 997         cable = loopback->cables[substream->number][dev];
 998         if (!cable)
 999                 return;
1000         if (cable->streams[!substream->stream]) {
1001                 /* other stream is still alive */
1002                 spin_lock_irq(&cable->lock);
1003                 cable->streams[substream->stream] = NULL;
1004                 spin_unlock_irq(&cable->lock);
1005         } else {
1006                 struct loopback_pcm *dpcm = substream->runtime->private_data;
1007
1008                 if (cable->ops && cable->ops->close_cable && dpcm)
1009                         cable->ops->close_cable(dpcm);
1010                 /* free the cable */
1011                 loopback->cables[substream->number][dev] = NULL;
1012                 kfree(cable);
1013         }
1014 }
1015
1016 static int loopback_jiffies_timer_open(struct loopback_pcm *dpcm)
1017 {
1018         timer_setup(&dpcm->timer, loopback_jiffies_timer_function, 0);
1019
1020         return 0;
1021 }
1022
1023 static const struct loopback_ops loopback_jiffies_timer_ops = {
1024         .open = loopback_jiffies_timer_open,
1025         .start = loopback_jiffies_timer_start,
1026         .stop = loopback_jiffies_timer_stop,
1027         .stop_sync = loopback_jiffies_timer_stop_sync,
1028         .close_substream = loopback_jiffies_timer_stop_sync,
1029         .pos_update = loopback_jiffies_timer_pos_update,
1030         .dpcm_info = loopback_jiffies_timer_dpcm_info,
1031 };
1032
1033 static int loopback_parse_timer_id(const char *str,
1034                                    struct snd_timer_id *tid)
1035 {
1036         /* [<pref>:](<card name>|<card idx>)[{.,}<dev idx>[{.,}<subdev idx>]] */
1037         const char * const sep_dev = ".,";
1038         const char * const sep_pref = ":";
1039         const char *name = str;
1040         char *sep, save = '\0';
1041         int card_idx = 0, dev = 0, subdev = 0;
1042         int err;
1043
1044         sep = strpbrk(str, sep_pref);
1045         if (sep)
1046                 name = sep + 1;
1047         sep = strpbrk(name, sep_dev);
1048         if (sep) {
1049                 save = *sep;
1050                 *sep = '\0';
1051         }
1052         err = kstrtoint(name, 0, &card_idx);
1053         if (err == -EINVAL) {
1054                 /* Must be the name, not number */
1055                 for (card_idx = 0; card_idx < snd_ecards_limit; card_idx++) {
1056                         struct snd_card *card = snd_card_ref(card_idx);
1057
1058                         if (card) {
1059                                 if (!strcmp(card->id, name))
1060                                         err = 0;
1061                                 snd_card_unref(card);
1062                         }
1063                         if (!err)
1064                                 break;
1065                 }
1066         }
1067         if (sep) {
1068                 *sep = save;
1069                 if (!err) {
1070                         char *sep2, save2 = '\0';
1071
1072                         sep2 = strpbrk(sep + 1, sep_dev);
1073                         if (sep2) {
1074                                 save2 = *sep2;
1075                                 *sep2 = '\0';
1076                         }
1077                         err = kstrtoint(sep + 1, 0, &dev);
1078                         if (sep2) {
1079                                 *sep2 = save2;
1080                                 if (!err)
1081                                         err = kstrtoint(sep2 + 1, 0, &subdev);
1082                         }
1083                 }
1084         }
1085         if (!err && tid) {
1086                 tid->card = card_idx;
1087                 tid->device = dev;
1088                 tid->subdevice = subdev;
1089         }
1090         return err;
1091 }
1092
1093 /* call in loopback->cable_lock */
1094 static int loopback_snd_timer_open(struct loopback_pcm *dpcm)
1095 {
1096         int err = 0;
1097         struct snd_timer_id tid = {
1098                 .dev_class = SNDRV_TIMER_CLASS_PCM,
1099                 .dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION,
1100         };
1101         struct snd_timer_instance *timeri;
1102         struct loopback_cable *cable = dpcm->cable;
1103
1104         /* check if timer was already opened. It is only opened once
1105          * per playback and capture subdevice (aka cable).
1106          */
1107         if (cable->snd_timer.instance)
1108                 goto exit;
1109
1110         err = loopback_parse_timer_id(dpcm->loopback->timer_source, &tid);
1111         if (err < 0) {
1112                 pcm_err(dpcm->substream->pcm,
1113                         "Parsing timer source \'%s\' failed with %d",
1114                         dpcm->loopback->timer_source, err);
1115                 goto exit;
1116         }
1117
1118         cable->snd_timer.stream = dpcm->substream->stream;
1119         cable->snd_timer.id = tid;
1120
1121         timeri = snd_timer_instance_new(dpcm->loopback->card->id);
1122         if (!timeri) {
1123                 err = -ENOMEM;
1124                 goto exit;
1125         }
1126         /* The callback has to be called from another work. If
1127          * SNDRV_TIMER_IFLG_FAST is specified it will be called from the
1128          * snd_pcm_period_elapsed() call of the selected sound card.
1129          * snd_pcm_period_elapsed() helds snd_pcm_stream_lock_irqsave().
1130          * Due to our callback loopback_snd_timer_function() also calls
1131          * snd_pcm_period_elapsed() which calls snd_pcm_stream_lock_irqsave().
1132          * This would end up in a dead lock.
1133          */
1134         timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
1135         timeri->callback = loopback_snd_timer_function;
1136         timeri->callback_data = (void *)cable;
1137         timeri->ccallback = loopback_snd_timer_event;
1138
1139         /* initialise a work used for draining */
1140         INIT_WORK(&cable->snd_timer.event_work, loopback_snd_timer_work);
1141
1142         /* The mutex loopback->cable_lock is kept locked.
1143          * Therefore snd_timer_open() cannot be called a second time
1144          * by the other device of the same cable.
1145          * Therefore the following issue cannot happen:
1146          * [proc1] Call loopback_timer_open() ->
1147          *         Unlock cable->lock for snd_timer_close/open() call
1148          * [proc2] Call loopback_timer_open() -> snd_timer_open(),
1149          *         snd_timer_start()
1150          * [proc1] Call snd_timer_open() and overwrite running timer
1151          *         instance
1152          */
1153         err = snd_timer_open(timeri, &cable->snd_timer.id, current->pid);
1154         if (err < 0) {
1155                 pcm_err(dpcm->substream->pcm,
1156                         "snd_timer_open (%d,%d,%d) failed with %d",
1157                         cable->snd_timer.id.card,
1158                         cable->snd_timer.id.device,
1159                         cable->snd_timer.id.subdevice,
1160                         err);
1161                 snd_timer_instance_free(timeri);
1162                 goto exit;
1163         }
1164
1165         cable->snd_timer.instance = timeri;
1166
1167 exit:
1168         return err;
1169 }
1170
1171 /* stop_sync() is not required for sound timer because it does not need to be
1172  * restarted in loopback_prepare() on Xrun recovery
1173  */
1174 static const struct loopback_ops loopback_snd_timer_ops = {
1175         .open = loopback_snd_timer_open,
1176         .start = loopback_snd_timer_start,
1177         .stop = loopback_snd_timer_stop,
1178         .close_cable = loopback_snd_timer_close_cable,
1179         .dpcm_info = loopback_snd_timer_dpcm_info,
1180 };
1181
1182 static int loopback_open(struct snd_pcm_substream *substream)
1183 {
1184         struct snd_pcm_runtime *runtime = substream->runtime;
1185         struct loopback *loopback = substream->private_data;
1186         struct loopback_pcm *dpcm;
1187         struct loopback_cable *cable = NULL;
1188         int err = 0;
1189         int dev = get_cable_index(substream);
1190
1191         mutex_lock(&loopback->cable_lock);
1192         dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
1193         if (!dpcm) {
1194                 err = -ENOMEM;
1195                 goto unlock;
1196         }
1197         dpcm->loopback = loopback;
1198         dpcm->substream = substream;
1199
1200         cable = loopback->cables[substream->number][dev];
1201         if (!cable) {
1202                 cable = kzalloc(sizeof(*cable), GFP_KERNEL);
1203                 if (!cable) {
1204                         err = -ENOMEM;
1205                         goto unlock;
1206                 }
1207                 spin_lock_init(&cable->lock);
1208                 cable->hw = loopback_pcm_hardware;
1209                 if (loopback->timer_source)
1210                         cable->ops = &loopback_snd_timer_ops;
1211                 else
1212                         cable->ops = &loopback_jiffies_timer_ops;
1213                 loopback->cables[substream->number][dev] = cable;
1214         }
1215         dpcm->cable = cable;
1216         runtime->private_data = dpcm;
1217
1218         if (cable->ops->open) {
1219                 err = cable->ops->open(dpcm);
1220                 if (err < 0)
1221                         goto unlock;
1222         }
1223
1224         snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
1225
1226         /* use dynamic rules based on actual runtime->hw values */
1227         /* note that the default rules created in the PCM midlevel code */
1228         /* are cached -> they do not reflect the actual state */
1229         err = snd_pcm_hw_rule_add(runtime, 0,
1230                                   SNDRV_PCM_HW_PARAM_FORMAT,
1231                                   rule_format, dpcm,
1232                                   SNDRV_PCM_HW_PARAM_FORMAT, -1);
1233         if (err < 0)
1234                 goto unlock;
1235         err = snd_pcm_hw_rule_add(runtime, 0,
1236                                   SNDRV_PCM_HW_PARAM_RATE,
1237                                   rule_rate, dpcm,
1238                                   SNDRV_PCM_HW_PARAM_RATE, -1);
1239         if (err < 0)
1240                 goto unlock;
1241         err = snd_pcm_hw_rule_add(runtime, 0,
1242                                   SNDRV_PCM_HW_PARAM_CHANNELS,
1243                                   rule_channels, dpcm,
1244                                   SNDRV_PCM_HW_PARAM_CHANNELS, -1);
1245         if (err < 0)
1246                 goto unlock;
1247
1248         /* In case of sound timer the period time of both devices of the same
1249          * loop has to be the same.
1250          * This rule only takes effect if a sound timer was chosen
1251          */
1252         if (cable->snd_timer.instance) {
1253                 err = snd_pcm_hw_rule_add(runtime, 0,
1254                                           SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
1255                                           rule_period_bytes, dpcm,
1256                                           SNDRV_PCM_HW_PARAM_PERIOD_BYTES, -1);
1257                 if (err < 0)
1258                         goto unlock;
1259         }
1260
1261         /* loopback_runtime_free() has not to be called if kfree(dpcm) was
1262          * already called here. Otherwise it will end up with a double free.
1263          */
1264         runtime->private_free = loopback_runtime_free;
1265         if (get_notify(dpcm))
1266                 runtime->hw = loopback_pcm_hardware;
1267         else
1268                 runtime->hw = cable->hw;
1269
1270         spin_lock_irq(&cable->lock);
1271         cable->streams[substream->stream] = dpcm;
1272         spin_unlock_irq(&cable->lock);
1273
1274  unlock:
1275         if (err < 0) {
1276                 free_cable(substream);
1277                 kfree(dpcm);
1278         }
1279         mutex_unlock(&loopback->cable_lock);
1280         return err;
1281 }
1282
1283 static int loopback_close(struct snd_pcm_substream *substream)
1284 {
1285         struct loopback *loopback = substream->private_data;
1286         struct loopback_pcm *dpcm = substream->runtime->private_data;
1287         int err = 0;
1288
1289         if (dpcm->cable->ops->close_substream)
1290                 err = dpcm->cable->ops->close_substream(dpcm);
1291         mutex_lock(&loopback->cable_lock);
1292         free_cable(substream);
1293         mutex_unlock(&loopback->cable_lock);
1294         return err;
1295 }
1296
1297 static const struct snd_pcm_ops loopback_pcm_ops = {
1298         .open =         loopback_open,
1299         .close =        loopback_close,
1300         .hw_free =      loopback_hw_free,
1301         .prepare =      loopback_prepare,
1302         .trigger =      loopback_trigger,
1303         .pointer =      loopback_pointer,
1304 };
1305
1306 static int loopback_pcm_new(struct loopback *loopback,
1307                             int device, int substreams)
1308 {
1309         struct snd_pcm *pcm;
1310         int err;
1311
1312         err = snd_pcm_new(loopback->card, "Loopback PCM", device,
1313                           substreams, substreams, &pcm);
1314         if (err < 0)
1315                 return err;
1316         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_pcm_ops);
1317         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_pcm_ops);
1318         snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
1319
1320         pcm->private_data = loopback;
1321         pcm->info_flags = 0;
1322         strcpy(pcm->name, "Loopback PCM");
1323
1324         loopback->pcm[device] = pcm;
1325         return 0;
1326 }
1327
1328 static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,
1329                                     struct snd_ctl_elem_info *uinfo)
1330 {
1331         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1332         uinfo->count = 1;
1333         uinfo->value.integer.min = 80000;
1334         uinfo->value.integer.max = 120000;
1335         uinfo->value.integer.step = 1;
1336         return 0;
1337 }
1338
1339 static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,
1340                                    struct snd_ctl_elem_value *ucontrol)
1341 {
1342         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1343
1344         mutex_lock(&loopback->cable_lock);
1345         ucontrol->value.integer.value[0] =
1346                 loopback->setup[kcontrol->id.subdevice]
1347                                [kcontrol->id.device].rate_shift;
1348         mutex_unlock(&loopback->cable_lock);
1349         return 0;
1350 }
1351
1352 static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,
1353                                    struct snd_ctl_elem_value *ucontrol)
1354 {
1355         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1356         unsigned int val;
1357         int change = 0;
1358
1359         val = ucontrol->value.integer.value[0];
1360         if (val < 80000)
1361                 val = 80000;
1362         if (val > 120000)
1363                 val = 120000;
1364         mutex_lock(&loopback->cable_lock);
1365         if (val != loopback->setup[kcontrol->id.subdevice]
1366                                   [kcontrol->id.device].rate_shift) {
1367                 loopback->setup[kcontrol->id.subdevice]
1368                                [kcontrol->id.device].rate_shift = val;
1369                 change = 1;
1370         }
1371         mutex_unlock(&loopback->cable_lock);
1372         return change;
1373 }
1374
1375 static int loopback_notify_get(struct snd_kcontrol *kcontrol,
1376                                struct snd_ctl_elem_value *ucontrol)
1377 {
1378         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1379
1380         mutex_lock(&loopback->cable_lock);
1381         ucontrol->value.integer.value[0] =
1382                 loopback->setup[kcontrol->id.subdevice]
1383                                [kcontrol->id.device].notify;
1384         mutex_unlock(&loopback->cable_lock);
1385         return 0;
1386 }
1387
1388 static int loopback_notify_put(struct snd_kcontrol *kcontrol,
1389                                struct snd_ctl_elem_value *ucontrol)
1390 {
1391         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1392         unsigned int val;
1393         int change = 0;
1394
1395         val = ucontrol->value.integer.value[0] ? 1 : 0;
1396         mutex_lock(&loopback->cable_lock);
1397         if (val != loopback->setup[kcontrol->id.subdevice]
1398                                 [kcontrol->id.device].notify) {
1399                 loopback->setup[kcontrol->id.subdevice]
1400                         [kcontrol->id.device].notify = val;
1401                 change = 1;
1402         }
1403         mutex_unlock(&loopback->cable_lock);
1404         return change;
1405 }
1406
1407 static int loopback_active_get(struct snd_kcontrol *kcontrol,
1408                                struct snd_ctl_elem_value *ucontrol)
1409 {
1410         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1411         struct loopback_cable *cable;
1412
1413         unsigned int val = 0;
1414
1415         mutex_lock(&loopback->cable_lock);
1416         cable = loopback->cables[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
1417         if (cable != NULL) {
1418                 unsigned int running = cable->running ^ cable->pause;
1419
1420                 val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;
1421         }
1422         mutex_unlock(&loopback->cable_lock);
1423         ucontrol->value.integer.value[0] = val;
1424         return 0;
1425 }
1426
1427 static int loopback_format_info(struct snd_kcontrol *kcontrol,
1428                                 struct snd_ctl_elem_info *uinfo)
1429 {
1430         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1431         uinfo->count = 1;
1432         uinfo->value.integer.min = 0;
1433         uinfo->value.integer.max = (__force int)SNDRV_PCM_FORMAT_LAST;
1434         uinfo->value.integer.step = 1;
1435         return 0;
1436 }
1437
1438 static int loopback_format_get(struct snd_kcontrol *kcontrol,
1439                                struct snd_ctl_elem_value *ucontrol)
1440 {
1441         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1442
1443         ucontrol->value.integer.value[0] =
1444                 (__force int)loopback->setup[kcontrol->id.subdevice]
1445                                [kcontrol->id.device].format;
1446         return 0;
1447 }
1448
1449 static int loopback_rate_info(struct snd_kcontrol *kcontrol,
1450                               struct snd_ctl_elem_info *uinfo)
1451 {
1452         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1453         uinfo->count = 1;
1454         uinfo->value.integer.min = 0;
1455         uinfo->value.integer.max = 192000;
1456         uinfo->value.integer.step = 1;
1457         return 0;
1458 }
1459
1460 static int loopback_rate_get(struct snd_kcontrol *kcontrol,
1461                              struct snd_ctl_elem_value *ucontrol)
1462 {
1463         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1464
1465         mutex_lock(&loopback->cable_lock);
1466         ucontrol->value.integer.value[0] =
1467                 loopback->setup[kcontrol->id.subdevice]
1468                                [kcontrol->id.device].rate;
1469         mutex_unlock(&loopback->cable_lock);
1470         return 0;
1471 }
1472
1473 static int loopback_channels_info(struct snd_kcontrol *kcontrol,
1474                                   struct snd_ctl_elem_info *uinfo)
1475 {
1476         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1477         uinfo->count = 1;
1478         uinfo->value.integer.min = 1;
1479         uinfo->value.integer.max = 1024;
1480         uinfo->value.integer.step = 1;
1481         return 0;
1482 }
1483
1484 static int loopback_channels_get(struct snd_kcontrol *kcontrol,
1485                                  struct snd_ctl_elem_value *ucontrol)
1486 {
1487         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1488
1489         mutex_lock(&loopback->cable_lock);
1490         ucontrol->value.integer.value[0] =
1491                 loopback->setup[kcontrol->id.subdevice]
1492                                [kcontrol->id.device].channels;
1493         mutex_unlock(&loopback->cable_lock);
1494         return 0;
1495 }
1496
1497 static const struct snd_kcontrol_new loopback_controls[]  = {
1498 {
1499         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1500         .name =         "PCM Rate Shift 100000",
1501         .info =         loopback_rate_shift_info,
1502         .get =          loopback_rate_shift_get,
1503         .put =          loopback_rate_shift_put,
1504 },
1505 {
1506         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1507         .name =         "PCM Notify",
1508         .info =         snd_ctl_boolean_mono_info,
1509         .get =          loopback_notify_get,
1510         .put =          loopback_notify_put,
1511 },
1512 #define ACTIVE_IDX 2
1513 {
1514         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1515         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1516         .name =         "PCM Slave Active",
1517         .info =         snd_ctl_boolean_mono_info,
1518         .get =          loopback_active_get,
1519 },
1520 #define FORMAT_IDX 3
1521 {
1522         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1523         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1524         .name =         "PCM Slave Format",
1525         .info =         loopback_format_info,
1526         .get =          loopback_format_get
1527 },
1528 #define RATE_IDX 4
1529 {
1530         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1531         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1532         .name =         "PCM Slave Rate",
1533         .info =         loopback_rate_info,
1534         .get =          loopback_rate_get
1535 },
1536 #define CHANNELS_IDX 5
1537 {
1538         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1539         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1540         .name =         "PCM Slave Channels",
1541         .info =         loopback_channels_info,
1542         .get =          loopback_channels_get
1543 }
1544 };
1545
1546 static int loopback_mixer_new(struct loopback *loopback, int notify)
1547 {
1548         struct snd_card *card = loopback->card;
1549         struct snd_pcm *pcm;
1550         struct snd_kcontrol *kctl;
1551         struct loopback_setup *setup;
1552         int err, dev, substr, substr_count, idx;
1553
1554         strcpy(card->mixername, "Loopback Mixer");
1555         for (dev = 0; dev < 2; dev++) {
1556                 pcm = loopback->pcm[dev];
1557                 substr_count =
1558                     pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;
1559                 for (substr = 0; substr < substr_count; substr++) {
1560                         setup = &loopback->setup[substr][dev];
1561                         setup->notify = notify;
1562                         setup->rate_shift = NO_PITCH;
1563                         setup->format = SNDRV_PCM_FORMAT_S16_LE;
1564                         setup->rate = 48000;
1565                         setup->channels = 2;
1566                         for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
1567                                                                         idx++) {
1568                                 kctl = snd_ctl_new1(&loopback_controls[idx],
1569                                                     loopback);
1570                                 if (!kctl)
1571                                         return -ENOMEM;
1572                                 kctl->id.device = dev;
1573                                 kctl->id.subdevice = substr;
1574
1575                                 /* Add the control before copying the id so that
1576                                  * the numid field of the id is set in the copy.
1577                                  */
1578                                 err = snd_ctl_add(card, kctl);
1579                                 if (err < 0)
1580                                         return err;
1581
1582                                 switch (idx) {
1583                                 case ACTIVE_IDX:
1584                                         setup->active_id = kctl->id;
1585                                         break;
1586                                 case FORMAT_IDX:
1587                                         setup->format_id = kctl->id;
1588                                         break;
1589                                 case RATE_IDX:
1590                                         setup->rate_id = kctl->id;
1591                                         break;
1592                                 case CHANNELS_IDX:
1593                                         setup->channels_id = kctl->id;
1594                                         break;
1595                                 default:
1596                                         break;
1597                                 }
1598                         }
1599                 }
1600         }
1601         return 0;
1602 }
1603
1604 static void print_dpcm_info(struct snd_info_buffer *buffer,
1605                             struct loopback_pcm *dpcm,
1606                             const char *id)
1607 {
1608         snd_iprintf(buffer, "  %s\n", id);
1609         if (dpcm == NULL) {
1610                 snd_iprintf(buffer, "    inactive\n");
1611                 return;
1612         }
1613         snd_iprintf(buffer, "    buffer_size:\t%u\n", dpcm->pcm_buffer_size);
1614         snd_iprintf(buffer, "    buffer_pos:\t\t%u\n", dpcm->buf_pos);
1615         snd_iprintf(buffer, "    silent_size:\t%u\n", dpcm->silent_size);
1616         snd_iprintf(buffer, "    period_size:\t%u\n", dpcm->pcm_period_size);
1617         snd_iprintf(buffer, "    bytes_per_sec:\t%u\n", dpcm->pcm_bps);
1618         snd_iprintf(buffer, "    sample_align:\t%u\n", dpcm->pcm_salign);
1619         snd_iprintf(buffer, "    rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);
1620         if (dpcm->cable->ops->dpcm_info)
1621                 dpcm->cable->ops->dpcm_info(dpcm, buffer);
1622 }
1623
1624 static void print_substream_info(struct snd_info_buffer *buffer,
1625                                  struct loopback *loopback,
1626                                  int sub,
1627                                  int num)
1628 {
1629         struct loopback_cable *cable = loopback->cables[sub][num];
1630
1631         snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);
1632         if (cable == NULL) {
1633                 snd_iprintf(buffer, "  inactive\n");
1634                 return;
1635         }
1636         snd_iprintf(buffer, "  valid: %u\n", cable->valid);
1637         snd_iprintf(buffer, "  running: %u\n", cable->running);
1638         snd_iprintf(buffer, "  pause: %u\n", cable->pause);
1639         print_dpcm_info(buffer, cable->streams[0], "Playback");
1640         print_dpcm_info(buffer, cable->streams[1], "Capture");
1641 }
1642
1643 static void print_cable_info(struct snd_info_entry *entry,
1644                              struct snd_info_buffer *buffer)
1645 {
1646         struct loopback *loopback = entry->private_data;
1647         int sub, num;
1648
1649         mutex_lock(&loopback->cable_lock);
1650         num = entry->name[strlen(entry->name)-1];
1651         num = num == '0' ? 0 : 1;
1652         for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)
1653                 print_substream_info(buffer, loopback, sub, num);
1654         mutex_unlock(&loopback->cable_lock);
1655 }
1656
1657 static int loopback_cable_proc_new(struct loopback *loopback, int cidx)
1658 {
1659         char name[32];
1660
1661         snprintf(name, sizeof(name), "cable#%d", cidx);
1662         return snd_card_ro_proc_new(loopback->card, name, loopback,
1663                                     print_cable_info);
1664 }
1665
1666 static void loopback_set_timer_source(struct loopback *loopback,
1667                                       const char *value)
1668 {
1669         if (loopback->timer_source) {
1670                 devm_kfree(loopback->card->dev, loopback->timer_source);
1671                 loopback->timer_source = NULL;
1672         }
1673         if (value && *value)
1674                 loopback->timer_source = devm_kstrdup(loopback->card->dev,
1675                                                       value, GFP_KERNEL);
1676 }
1677
1678 static void print_timer_source_info(struct snd_info_entry *entry,
1679                                     struct snd_info_buffer *buffer)
1680 {
1681         struct loopback *loopback = entry->private_data;
1682
1683         mutex_lock(&loopback->cable_lock);
1684         snd_iprintf(buffer, "%s\n",
1685                     loopback->timer_source ? loopback->timer_source : "");
1686         mutex_unlock(&loopback->cable_lock);
1687 }
1688
1689 static void change_timer_source_info(struct snd_info_entry *entry,
1690                                      struct snd_info_buffer *buffer)
1691 {
1692         struct loopback *loopback = entry->private_data;
1693         char line[64];
1694
1695         mutex_lock(&loopback->cable_lock);
1696         if (!snd_info_get_line(buffer, line, sizeof(line)))
1697                 loopback_set_timer_source(loopback, strim(line));
1698         mutex_unlock(&loopback->cable_lock);
1699 }
1700
1701 static int loopback_timer_source_proc_new(struct loopback *loopback)
1702 {
1703         return snd_card_rw_proc_new(loopback->card, "timer_source", loopback,
1704                                     print_timer_source_info,
1705                                     change_timer_source_info);
1706 }
1707
1708 static int loopback_probe(struct platform_device *devptr)
1709 {
1710         struct snd_card *card;
1711         struct loopback *loopback;
1712         int dev = devptr->id;
1713         int err;
1714
1715         err = snd_devm_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
1716                                 sizeof(struct loopback), &card);
1717         if (err < 0)
1718                 return err;
1719         loopback = card->private_data;
1720
1721         if (pcm_substreams[dev] < 1)
1722                 pcm_substreams[dev] = 1;
1723         if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1724                 pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1725
1726         loopback->card = card;
1727         loopback_set_timer_source(loopback, timer_source[dev]);
1728
1729         mutex_init(&loopback->cable_lock);
1730
1731         err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);
1732         if (err < 0)
1733                 return err;
1734         err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]);
1735         if (err < 0)
1736                 return err;
1737         err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0);
1738         if (err < 0)
1739                 return err;
1740         loopback_cable_proc_new(loopback, 0);
1741         loopback_cable_proc_new(loopback, 1);
1742         loopback_timer_source_proc_new(loopback);
1743         strcpy(card->driver, "Loopback");
1744         strcpy(card->shortname, "Loopback");
1745         sprintf(card->longname, "Loopback %i", dev + 1);
1746         err = snd_card_register(card);
1747         if (err < 0)
1748                 return err;
1749         platform_set_drvdata(devptr, card);
1750         return 0;
1751 }
1752
1753 #ifdef CONFIG_PM_SLEEP
1754 static int loopback_suspend(struct device *pdev)
1755 {
1756         struct snd_card *card = dev_get_drvdata(pdev);
1757
1758         snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1759         return 0;
1760 }
1761
1762 static int loopback_resume(struct device *pdev)
1763 {
1764         struct snd_card *card = dev_get_drvdata(pdev);
1765
1766         snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1767         return 0;
1768 }
1769
1770 static SIMPLE_DEV_PM_OPS(loopback_pm, loopback_suspend, loopback_resume);
1771 #define LOOPBACK_PM_OPS &loopback_pm
1772 #else
1773 #define LOOPBACK_PM_OPS NULL
1774 #endif
1775
1776 #define SND_LOOPBACK_DRIVER     "snd_aloop"
1777
1778 static struct platform_driver loopback_driver = {
1779         .probe          = loopback_probe,
1780         .driver         = {
1781                 .name   = SND_LOOPBACK_DRIVER,
1782                 .pm     = LOOPBACK_PM_OPS,
1783         },
1784 };
1785
1786 static void loopback_unregister_all(void)
1787 {
1788         int i;
1789
1790         for (i = 0; i < ARRAY_SIZE(devices); ++i)
1791                 platform_device_unregister(devices[i]);
1792         platform_driver_unregister(&loopback_driver);
1793 }
1794
1795 static int __init alsa_card_loopback_init(void)
1796 {
1797         int i, err, cards;
1798
1799         err = platform_driver_register(&loopback_driver);
1800         if (err < 0)
1801                 return err;
1802
1803
1804         cards = 0;
1805         for (i = 0; i < SNDRV_CARDS; i++) {
1806                 struct platform_device *device;
1807                 if (!enable[i])
1808                         continue;
1809                 device = platform_device_register_simple(SND_LOOPBACK_DRIVER,
1810                                                          i, NULL, 0);
1811                 if (IS_ERR(device))
1812                         continue;
1813                 if (!platform_get_drvdata(device)) {
1814                         platform_device_unregister(device);
1815                         continue;
1816                 }
1817                 devices[i] = device;
1818                 cards++;
1819         }
1820         if (!cards) {
1821 #ifdef MODULE
1822                 printk(KERN_ERR "aloop: No loopback enabled\n");
1823 #endif
1824                 loopback_unregister_all();
1825                 return -ENODEV;
1826         }
1827         return 0;
1828 }
1829
1830 static void __exit alsa_card_loopback_exit(void)
1831 {
1832         loopback_unregister_all();
1833 }
1834
1835 module_init(alsa_card_loopback_init)
1836 module_exit(alsa_card_loopback_exit)